FIELD OF THE INVENTION
The invention relates to a device for forming a sheet pile in a delivery of a sheet-fed printing press, the device having jogging plates for jogging edges of the sheet, the jogging plates being disposed perpendicularly to a lateral surface of the sheet pile and driven so as to be movable in a stationary sheet guide and to a sheet stop, respectively, the sheet stop being adjustable, if necessary or desirable.
Devices of this general type have become known heretofore. The published German Patent Document DE 29 42 855 C2, for example, describes a device wherein jogging plates are disposed at vertical sheet-pile sides of a delivery and are attached to an electromagnetic oscillating drive. The jogging plates thus execute oscillating movements in an approximately horizontal direction, thereby thrusting against the sheet edges. With this heretofore known device, the oscillation frequency is preferably of 10 Hz, i.e., far below the mains or line frequency and only slightly above the sheet-depositing frequency of high-speed sheet-fed offset printing presses which are presently capable of delivering three to five sheets per second. Moreover, the jogging plates, with respect to the jogging movement thereof, remain mechanically guided, which results in wear and tear and in a reduction of the service life of the jogging device.
It is also been known heretofore to use mechanical drives such as crank drives, cam-type drives, and the like as drives for jogging plates, such as is described, for example, in the published German Patent Document DE 42 21 660 A1 and the German Patent DE 30 01 356. Furthermore, German Patents DE 27 51 525 and DE 30 01 354 disclose pneumatic mechanical jogging drives. None of these drives, as well, is free of wear and tear, and consequently has to be maintained, i.e., serviced, or replaced after a given period of operation.
Moreover, most of the prior-art jogging devices are operated in accordance with the cycle of the sheet delivery and an integral multiple of the delivery frequency, respectively.
With increasing machine speeds, this conventional type of drive causes problems such as an excessive development of noise, in addition to the aforementioned wear and tear. Furthermore, with these heretofore known devices, the quality of the sheet piles which are delivered is not always satisfactory.